Search

Long-term experiments are an important tool to investigate the effects of crop rotation and fertilization measures under climate change conditions. However, there are few studies on nitrogen use efficiency (NUE) of crops in long-term cropping systems in Europe, but no consolidate studies in Germany. We analyzed a long-term experiment established in 1982 to observe the role of legumes on total nitrogen uptake, NUE, agronomic efficiency, nitrogen response index and N recovery efficiency compared to fallow land and cereals in a crop rotation over the long-term. The experiment included five different precrops (fallow land, maize, oat, field bean and clover mulch) in combination with four levels of fertilization (control, PK, PK+N with reduced dosage, and PK+N with full dosage followed by three years of cereal cultivation (winter wheat, winter rye, summer barley) in all treatments. The field trial was conducted as a fully factorial split plot design, with spatially randomized field repetitions in four blocks. Long-term mineral NPK fertilization improved the N uptake of winter wheat (185.7 kg N ha−1), winter rye (152.2 kg N ha−1) and summer barley (92.2 kg N ha−1) when the higher level of fertilization (NPK 100%) was implemented. A year-round application of clover mulch as green manure in the rotational system resulted in higher NUE (up to 37%) compared to fallow land after 40 years. Crop rotation with oat and maize (100% cereals) led to lower NUE (up to 30%) compared to fallow land. Clover mulch (198%), field bean (155%), fallow land (148%) and maize (119%) significantly increased the N uptake of wheat compared to oat in 2015. Over time, the agronomic efficiency was increased. This increase was 4 or 5 times higher in the 9th and 10th crop rotation compared to the beginning of the experiment (in 1983). Nitrogen response index of clover mulch was approximately 33–37% lower than fallow land at the beginning of the experiment in 1983 and 45–50% lower over the 40 years. N recovery efficiency values of winter wheat (94%), winter rye (66%) and summer barley (46%) increased within the 10th crop rotation compared to the beginning of the long-term experiment. Combining clover mulch as a green manure with mineral fertilizer has greater potential to improve NUE and crop productivity by increasing soil N availability. Our study highlights the importance of evaluating agronomic management practices in long-term field experiments to understand their sustainable effects. • Soil nutrition is regulated by the quality & quantity of plant residues incorporated into the soil. • Long-term application of green mulch and mineral fertilizer improves NUE and crop productivity. • After 40 years, agronomic efficiency was about 4 or 5 times higher than at the beginning of the experiment in 1983. • Nitrogen response index of clover mulch was about 33–37% lower than fallow at onset of the experiment. [ABSTRACT FROM AUTHOR]

High productivity and yield stability over time in combination with a reduction in the crop failure risk are the principal goals of both conventional and organic agriculture. These goals are achieved in organic agriculture through the maintenance of soil fertility and soil functions through agronomic practices such as balanced crop rotations and the application of organic amendments. Reduced tillage constitutes an important practice that limits the disturbance to the soil structure and biota, but deep ploughing is frequently used in organic farming for weed control and aeration of heavy soils. This study aimed to assess the impact of mixed organic farms and farms without livestock, so called stockless farms, with their respective crop rotations and fertilization management, and the effect of reduced tillage on yield dynamics. We compared yield dynamics i.e., crop yield, yield stability and the production risk, of three organic farming systems involving four levels of tillage intensity each at the Organic Arable Farming Experiment Gladbacherhof (OAFEG), Germany, based on a long-term (24 year) dataset. The six-year crop-rotation of a mixed farm was compared to stockless farming with rotational alfalfa ley and stockless farming with cash crops. The levels of tillage intensity ranged from deep inversion ploughing to non-inversion tillage. The yield data from the OAFEG trial were evaluated with respect to the mean yield data from all cropland systems at Gladbacherhof research farm. We calculated the yield dynamics of the complete crop rotation as well as three crops within the rotations i.e., winter wheat, winter rye and potato. The most promising combination of high yield and yield stability was mixed farming with deep (30 cm) and shallow (15 cm) ploughing, in contrast to stockless farming (with ley) with non-inversion tillage. Similar results were recorded for cereals, but not for potatoes. Stockless farming with cash crops and non-inversion tillage had the highest production risk, i.e., the highest probability of falling below the defined critical yield level. Under the predominant heavy soil conditions in central Germany, non-inversion tillage can't keep up with inversion tillage regarding a stable organic production. Mixed farming with livestock which is representative of traditional organic farming system was found to produce high yields, but also stockless farming with rotational alfalfa ley was competitive. Stockless or "vegan" organic farming can be an alternative production system to organic mixed farming with stable yields provided that rotational alfalfa ley is part of the crop rotation. Ploughing depth can be reduced without affecting productivity. [Display omitted] • Stockless farming with ley and inversion ploughing shows high and stable yield. • Shallow ploughing is a promising alternative to deep ploughing in respect to yields. • Worst yield dynamics with non-inversion tillage in all farming systems. • Farming system and tillage affect yield of winter cereals wheat and rye in a comparable way. • Potato yield dynamics were independent from long-term tillage effects. [ABSTRACT FROM AUTHOR]

Empirical data on energy performance (net-energy yield, energy efficiency, land demand) of biomass crop cultivation are needed for policy and agronomic decision making. Energy input and energy performance of the cultivation of silage maize (SM), sugar beet (SB), and winter wheat (WW) in crop rotations and continuous cultivation were evaluated on the basis of three field experiments on highly productive sites in Germany. Silage maize and SB root were considered as crops for biogas production and WW as a food crop. Even if SM cultivation needed the largest energy input across sites and years (19–22 GJ ha −1 a −1 ), the energy output compensated for it and largest net-energy yield (212–317 GJ ha −1 a −1 ), energy efficiency (11.4–17.1 GJ GJ −1 ), and smallest land demand (33–48 m 2 GJ −1 ) were observed. For SB cultivation, energy input (15–19 GJ ha −1 a −1 ) and energy performance were lower (119–266 GJ ha −1 a −1 , 9.1–14.7 GJ GJ −1 , 38–279 m 2 GJ −1 , respectively). Differences between both crops were significant (p ≤ 0.05), but not in all cases. Winter wheat cultivation required an energy input of 13–18 GJ ha −1 a −1 and showed the lowest energy performance (103–119 GJ ha −1 a −1 , 6.6–8.6 GJ GJ −1 , 84–102 m 2 GJ −1 , respectively). The net-energy yield and land demand values presented are among the largest and the lowest, respectively, for rainfed Central European conditions. As the preceding crops, SB induced a higher energy performance of the subsequent WW than SM. When taking such crop rotation effects into account for the overall evaluation, we concluded that SB root as a biomass crop is a suitable alternative to SM. [ABSTRACT FROM AUTHOR]

• No-tillage gains lower yield than plow tillage with sandy soil and low precipitation. • No-tillage signigicantly nagatively influences silage maize yield after 3 years. • Achieving approximate double yield by irrigation in extreme drought years. • Irrigation is the most important factor as compared to tillage and crop rotation. • Giving highest and stable yield under plowed, irrigated and crop rotation combination. To analyze the effects of tillage (no-tillage , plow tillage), irrigation (rainfed , irrigated), and crop rotation (continuous maize , 4-year crop rotation) and their development, we conducted a field experiment over 9 years under sandy soil conditions in northeastern Germany. The generalized linear model showed that tillage, irrigation and crop rotation jointly explained approximately 35% of the total variance. Irrigation and crop rotation significantly positively influenced maize biomass yield started immediately in the first years in 2008 and 2011 respectively, while tillage started to significantly positively affect yield starting from the fourth year. In general, irrigation had the most relative importance as a management factor compared to the importance of tillage and crop rotation. Crop rotation with legumes increased soil nitrogen and carbon content and led to a higher yield than continuous maize 11.1 dt ha−1 y−1 in average. Furthermore, the significant effect of crop rotation on the yield of the following crop (maize) continued after 2 cycles of a 4-year crop rotation. A significant influence of the 2-way interactions between rotation, tillage and irrigation was only found in extremely dry years. It can be concluded that (i) the negative influence of no-tillage becomes noticeable after 3 years, leading to significantly lower yield compared to plow tillage; (ii) under the sandy soil and dry conditions, irrigation significantly increases yields and is the most important factor compared to tillage and crop rotation; and (iii) crop rotation significantly increases and maintains maize yield under both plowed and irrigated conditions. [ABSTRACT FROM AUTHOR]